Film holder for radiographic examination of pipe welds



Sept. 22, 1959 H. J THIELSCH FILM HOLDER FOR RADIOGRAPHIC EXAMINATION OFPIPE WELDS Filed Oct. 8, 1956 rif FIG. 2

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United States Patent O FILM HOLDER FOR RADIOGRAPHIC EXAMINATION OE PIPEWELDs Helmut J. Thielsch, Providence, RJ., assignor to GrinnellCorporation, Providence, R.I., a corporation of Delaware ApplicationOctober 8, 1956, Serial No. 614,535

7 Claims.A (Cl. Z50-68) This vinvention relates to an apparatus formaking radiographic examinations of pipe welds.v

' More particularly, this invention relates to a radiographic filmholder which, by the passage of a coolant fluid therethrough protectsthe film from high temperatures following the welding process. Thesehigh temperatures, which could destroy the film, are due to the heatremaining .in the pipes after the application of a layer of weld metaland may also be due to heating by induction coils which are used tomaintain the pipes at a pre-heat or minimum temperature in order toprevent the formation of cracks in the weld.

In the Welding of pipe ends, especially those of steel, it is oftendesirable to examine the weld after one or more layers of the weld metalhave been deposited. To eiect this examination one `of the more commonmethods has been to employ radiographic film. This film is placed on oneside of the weld and a radioactive source, such as radium, is placed onthe other side. The emanations from the radioactive source pass throughthe weld and strike the film, thus activating the film emulsion. After asuitable exposure time the film, termed a radiograph, is developed andinspected and the quality of the weld, as indicated by the absence ofimperfections such as oxides, cracks and fissures, may be determined. lfmore than a single layer of weld metal is applied, as in the k weldingof pipes having very thick walls, this process of radiographicinspection is occasionally used after the completion of several suchlayers of Weld material.

While radiographic inspection may be made after the pipes have cooled totemperatures below those which would destroy the film sensitivity, thecooling times involved are long and therefore costly, especially withlar-ge size pipes wherein a plurality of weld layers must be deposited'to complete the joint.

TO protect radiographicffilm `during the inspection of pipe welds theprior'art has evolved a rigid jacket which is secured to the Outside ofthe weld close to the pipe, which supports -the film adjacent portionsof the weld and through which water passes between the lm and the weldto protect the film from the heat of the pipes.

One diliiculty with this prior art arrangement has been that a rigidjacket which fits closeto the exterior pipe surface cannot convenientlybe used with more than one pipe size and hence a jacket must be preparedfor each size or for a relatively few sizes. Another disadvantage hasbeen that the film carried by these jackets has not extended entirelyaround the weld but only along a portion of the circumference thereof,so that several exposures have had to be made in order to completelyinspect asingle weld layer. Finally, it has been a disl advantage of theprior art device that because the passage of the cooling iiuid has beenbetween the weld and the film, impurities in the water such as mineralsand deposits on the interior of the coolant passageway will appear onthe film and may give false indications of weld faults.

Accordingly, it is an object of this invention to provide ICC ' animproved film-holding water jacket to protect radiographic film used forinspection of a weld.

It is a further object of this invention to provide an improvedfilm-holding water jacket wherein the film placed thereon completelyencompasses the weld whereby a single film exposure to radioactiveemanations yields a radiograph of the entire weld.

vIt is a further object to provide an improved film-holding water jacketwhich may be used to hold radiographic film on pipes 'of differentdiameters.

It is another Object of this invention to provide an improvedfilm-holding water jacket wherein the emanations from a radioactivesource do not pass through a volume of water before striking the film.

These and other objects will become apparent from the followingdescription of the invention;

` In the drawings:

Fig. l is a perspective View of a preferred film-holding water jacketaccording to the invention, the jacket being broken to illustrate itscross-section; v

Fig. 2 is a side elevation view showing the film-holding water jacket ofFig. l wrapped around a pipe weld and carrying a photographic film; and

Fig. 3 is a fragmentary cross-section view showing the film-holdingjacket of Fig. 2 in position at the outside surface of the pipe endsacross the weld.

Referring to the drawings, the numeral 10 denotes a preferred embodimentof a film-holding water jacket according to this invention which isfashioned from a flexible strip 12 of copper or other material having ahigh heat conductivity. The strip is bounded on its sides by spirallywound tiexible vconduits 14 of copper or other material also having ahigh heat conductivity. Each side of the strip is soldered or brazed tothe conduit, at locations therealong several of which are indicated atV15, thus making a joint through which heat may readily pass from thestrip to the conduits and which permits exing of the strip and conduit.At onerend of the strip 12,

the conduits 14 terminate within the bent ends of a transverselyextending tubular portion 16. A tubular extension 18 is secured at oneof its ends to portion 16 and at its other end carries 'a pipe union 20.Eyes 22 are spaced along the portion 16. y k j At the other end of thestrip the conduits14 terminate within the bent ends of outwardlyextending tubular segments 24 which in turn terminate in the ends ofupwardly extending tubular segments 26, the other ends of which arejoined by a transversely extending tubular segment 2S, also havingspaced eyes 22 thereon. A tubular extension 30 is secured at one end tothe segment 2S and carries a union 32 at its other end.

The segments 24, 26,V and 28 form an opening 33 which can receive thetubular portion 16 so that this portion and the elements 18 and 20carried thereby may be inserted into the opening in the overlappingposition shown in Figs. l and 2. From the yfurther description whichfollows, it will be seen that` the tubular portion 16, extension 18,segments 24, 26, 28 and extension 30 need not be iiexible but may beformed of relatively rigid conduit material such as copper tubing.

In Fig. 2 of the drawings, the film holder is shown -applied to a weldjoining two pipes 34 and 36 while a radiograph is being made. The holderis shown Wrapped around the weld with the elements 16, 18 and 20`inserted in the opening 33 and with the ends of the strip 12overlapping. A radiographic film 38 is located4 on the exterior portionofthe strip l12 with its ends also preferably overlapping.' Elasticbands 40 having hooks 42. are drawn around the film and the hooks 42placed in the eyes 22. These bands maintain the jacket in a contractedconfiguration so that it snugly encompasses the weld area of the pipesvand a1so-maintainsthelm 38 in position. A plug 44extendingthrough ahole45-in oneA ofthe pipeshas an extension 46 which carries a radioactivesource 48 such as radium substantially into the plane of the Weld andsubstantially/atthe.. axis ofthe pipesf34 and 36. `l'ig. 3, which is afragmentary cross-section view ofthe assembly of Fig. 72,shows-emanations 49 from the Yradioactive source148 passing through theweld area to the film 38.

A-coolant, usually water, passes through a hose 50 connectedto union '32and divides at the junction of segments 30 and 28. Then the coolantpassesthrough the conduits E14 and thence through portions 16, 18,.union20 andout :through hose 52. The jacket is left in the position shown inFig/2 until the emanations tromlthe radioactive source-48 passingthroughzthe weld activate the lm, `thus making a radiograph `of theweld. Because-the ends of theilm A38 overlap, the entire extent of theweld may be examined ina single exposure.

v#Whentheflmiholder is placed around the weld area as shown in Fig. 2,and during the exposure, the temperature at the weld area is ordinarily-between 500 and 600 F. This order of temperature must be maintained inwelding .certain metals and particularly in welding heavy walled pipe toprevent cracking of the weld layers. Accordingly, heating inductioncoils 54 are employed for this purpose. Theyfmay be wrapped around anasbestos covering 56 on the pip.

The iilm 38 is protected from the heat in the weld area by the shieldingeiect of the strip 12 the temperature of which does not rise above thesafe temperature for the lm due to the rapid conduction of heat from thestrip to the exible conduits 14 and thence to the circulating coolantvtluid which carries it away.

Despite corrosion of or accumulation of mineral deposits on the interiorof the exibletconduits 14, the radiograph will not be affected since theradioactive emanations which pass through the weld (see Fig. 3) andactivate the iilm do not also pass through the coolant passages.

The following table will illustrate the advantageous results attendantthe use of this invention. The entries are given for a weld wherein thepipe sections were 12 inches outside diameter with a wall thickness of1.3 inches. The pipe temperature was 550 F. and the coolant (water)ilow` rate was 2.2 gallons per minute. The strip 12 was .025 `inchthick, the flexible tubing was 3A; inch in diameter and both were ofcopper.

The foregoing description shows that none of the emanations which reachnthe film passes rst through .the cooling water. This. can be otherwisedescribed with vfurther reference to Fig. 3 in which it .will be seenthat a -rst zone 58 located entirely'on the pipe-side of the strip 12 isdefined by lines 49 .drawn from the radioactive source-48 (which isonaline perpendicular to the .strip 12) to theedges 600i?` the surface.which the lm covers. Additional zonesf61 may be dened by lines 62emanating fromy the radioactive source 48.and extending tothoseportions.oftheconduits 14 which lie on the .pipe-.side ofthestrip; 12. In anygivenrarrangement the portions .(if any). of the conduits 14 which thuslie on the vpipe-side'of the strip 12 can -be determined lby drawing aline y64 which extends the plane of the strip 12 and by 4 thendetermining Wherev this line passes through the conduit.

I claim:

l. A tlm holder assembly for radiographic examination of weldsincluding: a strip of heat conductive material having one side adaptedto be presented to a weld and having a surface on,-the, opposite sideadapted to be covered bya lrn, a rstzoneentirely on ,sail'one side ofsaid strip deiined by the edgesof said surface and a point which islocated on said one side of said strip on aline. extending perpendiculartherefrom and-fromwhich emanations. oneadoptedto radiate, and aconduit'oft heat conductive material dening a duid path, Said conduitbeing Ajoined to said strip and vextending substantially lengthwisetherealong, a second zone which is also entirely on said one sideofsaidstrip rand which is dened by said point and by the boundaries ofany portion of said conduit which is on said one side of said strip, anda substantialportion of said iirst-zone being noncoextensive with saidsecond zone, whereby said l-m may be presented. to asource ofwemanations withoutobstruction -byuid in said conduit.

2. A lm holder assembly as vset -forth in claim 1 wherein said conduitis secured to one, edge .ofaidstrip along the length thereof. i

3. A lm holder assembly for radiographic examination of welds including:a strip of. heatconductivematerial having one side adapted to bepresented to la weld and to a source of emanations on the other sideof-vsaid weld and having a Surface on theopposite -sideadapted to becovered by `a radiagraphic iilm, and `a pair of conduits of heatconducting material each dening-.a uid path, said conduits being securedto the yedgesof said `strip andY extending substantially lengthwisetherealong, and a substantial portion of said strip being located remotefrom said conduits.

4. An assemblywfor the radiographic examination -of welds including: apipe Weld, va tilm holder locatedon and around the weld, said holdercomprising a strip of heat conductive material and a conduit of heatconductive material defining a uid path, said conduit `being' joined tosaid Strip -and extending substantially lengthwise there along, a lmsensitive to radioactiveemana'tions andllocated on the side of the stripremote from said weld,. said 'lm spaced laterally from said conduit, andone end1 of said strip overlapping the other end thereof.

5. A lilm holder assembly for radiographicfexamination of-weldsincluding: Va exible strip element of-heat conductivematerial havingoneside adapted. torfbevpresented to a weld and having its oppositeside-adapted to receive a nlm, a pair Yof conduitelements-ofheatconductive material each defining a tiuid path, saidconduit elements being secured to the edges ofsaid stripclement, a firsttting element connecting Said eonduitelements to a common fluid supplyat one, end -ofsaid-,assembly and a second fitting connecting saidconduit elements -to a common uid outlet at theotherfend of saidassembly, one of said tting elementsdening a boundary References ,Citedin the tile of this patent UNITEDV STATES" PATENTS 2,494,740 Boucher g l..r af1an. 17, *1950 2,587,056 McElroy et al. Feb.2v6, 1952

